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Climate Change Science:An introductionPS399: Science and Politics of Climate ChangeRonald B. MitchellUniversity of Oregon1Why should we trust the science and which science should we trust?Credible sources: expertise and trustworthinessIndividuals using scientific methodSociology of science and peer review; institutionally conservative IPCCStrong social expectations of truth-tellingConfirmation of predictions from theoryMultiple independent sources of same infoMultiple indicators of same trendBest explanation, not just a possible explanationAccounting for all data, not just selected dataTrust the preponderance of skeptically-evaluated evidence not the consensusSome Basics3Brief History of Climate Governance4Weather vs. climateClimate = the average weather. Weather is chaotic, climate is not.Climate is what you expect, weather is what you get.Why can we predict climate but not weather?Can predict June climate but not June weather Know Eugene is wetter than Phoenix even though it may rain in either & cant predict perfectly if it will tomorrowAlways easier to predict an average5Go to source for this infoIPCC Climate Change 2014http://www.ipcc.ch/-- Synthesis Report-- Physical Science Basis-- Impacts, Adaptation and Vulnerability -- Mitigation of Climate Change

6Earths Heat-trapping Blanket7

IPCC: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-3-figure-1.htmlThe Climate System8

Is human-caused climate change occurring?Better phrased as: are human actions causing Earths climate to change in ways that differ enough from historical natural variation that we are likely to face impacts that humans find unattractive?Two subquestionsIs the climate changing?Are humans the cause of the changes we are seeing?9Is the Climate Changing?10Is climate changing? Yes. Whats the evidence?Temperatures as measured are increasing over time, with various measurement types consistent with each other: thermometers / ice cores / corals / tree rings / land and ocean temps / satellitesOther direct indicators that warming has occurred: glaciers / ice sheets / Arctic ice / sea level rise / date of river-ice breakup / precipitation changesCanNOT attribute single events to climate change but can attribute probability shifts to itIndirect indicators of warming also consistent with warming: bird migration days / plant blooming daysAmount of warming appears to be outside natural variationRate of warming appears to be faster than natural variation11Multiple ways of measuring temperature increaseThermometers for recent past averaged across globeIce core records for long-range pastCorals and ocean sediments for long-range pastTree rings for medium-range pastSatellites for present and futureWherever these methods overlap, good consistencyWhere they measure different things, good consistency12Thermometer Record for Past 140 YearsSource: Intergovernmental Panel on Climate Change. 2001. Climate change 2001: the scientific basis, summary for policymakers (a report of Working Group I of the Intergovernmental Panel on Climate Change). Geneva: Intergovernmental Panel on Climate Change, 3.

13Ice Core Record for Past 1000 Years Source: Intergovernmental Panel on Climate Change. 2001. Climate change 2001: the scientific basis, summary for policymakers (a report of Working Group I of the Intergovernmental Panel on Climate Change). Geneva: Intergovernmental Panel on Climate Change, 3. At: http://www.ipcc.ch/present/cop65/johnhoughton.ppt

14Multiple locations of warming15

Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased (IPCC, 2013).Other direct indicators of warmingPrecipitation: Changing patternsGlaciers: RecedingSea levels: RisingSea ice : DecliningRiver ice breakup: EarlierExtreme climate events: More frequent16Precipitation: Changing patterns17

Source: IPCC, 2013Glaciers: Receding18

IPCC: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-4-13.html Greenland glacier loss long time trend of one caseGlacier loss pictures numerous cases of same phenomenonGlaciers: Argentina

http://news.bbc.co.uk/2/shared/spl/hi/picture_gallery/05/sci_nat_how_the_world_is_changing/html/1.stmGlaciers: AustriaSource: Gesellschaft fr kologische Forschung e.V. 2002. Das gletscherarchiv. http://www.gletscherarchiv.de/. Accessed on: 15 January 2003.

Krnten, Austria20Sea levels: Rising21Source: IPCC, 2013: The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia.

Sea ice: decliningArctic sea ice loss 1900-201o long time trend of large phenomenon (~3.5%/decade)

changes in BAntarctic sea ice loss little evidence of long-term changes in max or min ice extent

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River ice breakup: Earlier

23River ice breakup: Columbia RiverColubmia River froze over in: 1830, 1833, 1840, 1842, 1847, 1849(2x), 1856, 1875, 1862, 1868, 1884, 1885, 1888, 1890, 1891, 1894, 1896, 1907, 1909, 1916, 1919, 1930 *

Picture: Hood River, Oregon, W. D. Rogers, 1/17/1907; Oregon Historical Society Photo OrHi 35431 (http://librarycatalog.ohs.org/) Columbia generally freezes up once in the winter from a trial in 1882 at http://books.google.com/books?id=wZA8AAAAIAAJ (p. 1393)*Data on freezes compiled from: http://www.pacificcohistory.org/columbia.htm; http://historyink.com/results.cfm?keyword=Weather&searchfield=topics; and http://www.nwmapsco.com/ZybachB/Thesis/05-081_Chapter_3b.pdf (p. 86)Extreme climate events: expected to be more frequentExpectation of more frequent and bigger: storms // droughts // floodsAll these occur regularly anyway, so these are about increased likelihood, which is more uncertainNo clear trend in tropical cyclones (IPPC, 2007).Insufficient evidence to determine whether trends exist in small-scale phenomena such as tornadoes, hail, lightning and dust storms (IPPC, 2007). No single event attributable to warming but can attribute changes in probability25Droughts more frequent

Palmer Drought Severity Index -3 = severe drought; -4 = extreme droughtIndirect indicators of warmingChanges in biological systemsBirds, butterflies, mammals migrating earlier in yearPlants blooming earlier in year Animals and plants moving: observed higher in altitude or latitude than previously

27Observed effects of climate changes28

Of the more than 29,000 observational data series, from 75 studies, that show significant change in many physical and biological systems, more than 89% are consistent with the direction of change expected as a response to warming IPCC, 2007)QUESTIONS?29Are humans the cause of the changes we are seeing?30Summary of humans as causes argumentHigher levels of human behaviors that lead to increased emissions of known climate-changing gasescorrelate with Higher atmospheric concentrations of those gases whichcorrelate with Higher temperatures (and as predicted temperaturesand do not correlate with Natural causes of higher temperatures aloneand are explainableBy well-known theories of physics and chemistry31Why should we think its humans?Physics and chemistry of planet temperature knownEarth in equilibrium; small changes can change thatIncreases in culprit chemicals seen in atmosphereCulprit chemicals come from known human activitiesTemperature changes coincide with concentration and human activity increasesModels match data only if natural factors and human factors included32Physics and chemistry of planet temperature knownBasic physics and chemistry say more GHGs, more temperatureRecord shows CO2-temperature correlation33CO2-temperature correlation34

Source: IPCC, 2013Earth in equilibrium:small changes can change thatCO2 and CH4 are VERY small fraction of atmosphereN2: 78%; O2: 21%; Ar: 1%; CO2: 0.04%; CH4: 0.0002%Small changes in inputs can make big changes in outputs. Delicate balance is in equilibrium: 500 pounds on each side, grain of sand can unbalance.Human body: 5 beers = (5* 12 * .05) 3 ounces of alcohol can influence a 2400 ounce person (150 pounds)35Increases in culprit chemicals seen in atmosphereCO2: Atmospheric concentrations over past 10,000 years between 260 and 280; Currently at about 400 and on a steady trajectory upward in last 60 years (Mauna Loa)CH4: Atmospheric concentrations before 1800 at 0.8 ppm; Began increasing in 1800 and now at 1.75 ppm (more than 2x)No other explanations of these changes36CO2 measured at Mauna Loa

Source: IPCC, 201337Culprit chemicals come from known human activities38IPCC: http://www.ipcc.ch/graphics/syr/fig2-1.jpg

Culprit chemicals come from known human activities

Source: World Resources Institute: http://www.wri.org/image/view/9529/_originalBasics of that chart:3 main greenhouse gases & their 4 sourcesHuman GHG emissions: up 70% from 1970-200475% of problem: Carbon Dioxide (CO2)Fossil fuel use for transport, electricity, heating, cooling, manufacturing (55%)Deforestation (20%)15% of problem: Methane (CH4)Livestock and manureRice cultivation8% of problem: Nitrous Oxide (N2O)Agriculture fertilizationTemperature changes coincide with concentration and human activity increasesMost coincide with industrial revolution around 1850Glacier record decline starts in 1850Sea level -- increase starts in 1850Since 1900: 1.5F (0.7C) rise in global surface air temp30% increase in CO2150% increase in CH4 (methane)Happening on HUMAN timescales, not ecological onesIf earth were 100 years oldThen man emerges ~ 1 day agoRecorded history started 2 hours agoIndustrial revolution started 2 minutes ago41

Models match data only if natural factors and human factors includedFive natural causes of climate change: Too slow: Tectonic processes, Earths orbitNot correlated with temp: Volcanos, Suns energy, Climate variabilityFew natural causes of increases in greenhouse effectGraphic representation of the matching: Computer models only match observations of temperature when BOTH natural and human forcings are included.42Strengthening evidence that humans are causing it: IPCC ReportsFAR: 1990: unequivocal detection of enhanced greenhouse gas effect not likely for decade or moreSAR: 1995: balance of evidence suggests a discernible human influence on global climateTAR: 2001: new, stronger evidence that most warming observed of last 50 years is due to humansAT4: 2007: most observed increase in global average temps since 1950 is likely due to anthropogenic greenhouse emissionsAT5: 2013: extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th centurySlide courtesy of Greg Bothun, U of OregonSummary of humans as causes argumentHigher levels of human behaviors that lead to increased emissions of known climate-changing gasescorrelate with Higher atmospheric concentrations of those gases whichcorrelate with Higher temperatures (and as predicted temperaturesand do not correlate with Natural causes of higher temperatures aloneand are explainableBy well-known theories of physics and chemistry4445Models match data only if natural factors and human factors includedBest match of data is when model includes both known forces that influence global temperatures

Models match data only if natural factors and human factors includedSea level (San Francisco) with natural factors that influence sea level identified 47

QUESTIONS?48